Motorola Droid Bionic :: Ticking Sound From Speaker -- When Not Using The Phone

For the first time, my Bionic started making a sound, somewhat between a slow crackle and a tick (although not perfectly regular in timing), that was audible with the phone setting on a sofa cushion. It sounded like it was coming from the area of the mic, but I suppose it was coming from the speaker on the rear near the bottom. I was not actively using any apps at the time, although Google Music and Pocket Casts had both been used (via Bluetooth headset) earlier today.

I tried sleeping the phone and waking it up, and the sound resumed. Power off, waiting a minute or two, and then power on seems to have fixed it, at least for the 10 or so minutes since I restarted it. For the record, this phone has been nearly 100% reliable -- the battery cover has never been off since leaving the Verizon store, about a week after launch.